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Stepping out from behind the podium on the stage of the Helen Bernstein High School auditorium in Hollywood, Tim Chaddick begins telling a story about trying to find a Wi-Fi signal for his iPhone one day when he was walking near the USC campus. "The first signal that came up," he says with a sparkly smile, "was one called UCLA Sucks." The crowd of about 1,500 overwhelmingly attractive twenty­somethings—many clad in skinny jeans and Converse and adorned with artistic tattoos—titters with laughter before Chaddick makes his point with some gravitas: "We so often define ourselves by what we're against."

Gleaning life lessons from wireless networks would be perfectly normal for a tech guru or a new-school motivational speaker. And the 31-year-old Chaddick looks the part, with blond bangs, a cleft chin, and crystal-blue eyes, not to mention his tight white short-sleeve button-down and tattooed arms. But really nothing he says indicates that he's anything other than a pastor: Amid his references to Facebook and apps, he quotes the fiery 19th-century British evangelist Charles Spurgeon and adds, "We look for satisfaction and value, worth and identity, in everything but God, and those things eventually pass away." The youthful, chic West Hollywood types who make up most of the audience aren't daunted—they've come to Reality LA, one of the fastest-growing born-again-Christian churches in Los Angeles, this Sunday morning for Chaddick's sermon on "the sin of radical self-centeredness." When Chaddick finishes, the lights dim and the church band breaks into U2-esque indie rock with devotional lyrics, and a swarm of thin, muscular bodies converges in front of the stage for Communion; afterward, some huddle—heads bowed, arms around each other—with members of Reality LA's prayer team. Others sway to the music, arms outstretched, eyes glistening. One guy in stovepipe jeans and a flannel shirt weeps openly.

While Reality LA's congregation has grown 50-fold since its inception four years ago, what makes its mushrooming popularity notable isn't that its message is spreading like wildfire but that it's so targeted. Across the country there are fire-and-brimstone churches for every ethnicity, for metalheads, for bikers, and for just about any kind of outlier and niche affinity group. Yet prior to the founding of Reality LA, no one was really bringing the Word to this particular demographic: young, attractive hipsters. If the boutique church—part of a network that launched in Carpinteria, near Santa Barbara, in 2006 and now has outposts in Ventura, Stockton, San Francisco, and London—has discovered how to tap this crowd's previously undetected Christian fervor, it may simply be because beautiful people like to commune with their own. Perhaps the Vampire Weekend set has always yearned for old-fashioned Sunday religion but just couldn't handle the RV-loving rabble associated with it.

Chaddick's church is the antithesis of mass-produced middle-American neo-Protestantism. While Joel Osteen's brand of cul-de-sac Christianity suggests that you can get a perfect, prosperous life and a six-bedroom mansion through faith and regular church attendance, Reality LA, which doesn't advertise itself, is at once much more reactionary and much hipper, the small-batch alternative to the Walmart-esque megachurch. Reality's teachings are distinctly antimaterialistic, instructing followers to screw the six bedrooms and forget about the house—the church encourages members who would donate money out of obligation not to give at all and rents a high school for worship rather than owning a building. Chaddick also preaches that being born-again isn't a magic bullet that will suddenly absolve you of sin or torment. "Our lives are ones of continual repentance, and to repent just means to turn away," he says. "Perfection is not required, but progress is possible."

This would seem like a tough doctrinal pill to swallow, especially to a crowd of young, fashion-forward Angelenos who look as perfect as the cast of any CW show. But Reality's traditional dogmas are balanced with frank discussions of the modern pressures faced by its flock. Chaddick, who was saved in 1999, two years after he graduated from high school, is open about the fact that when he was coming of age, in Sonoma, California, he discovered "a little unholy Trinity" of sex, drugs, and rock and roll. As a teen he became addicted to crystal meth and had the kind of casual attitude toward sex that resulted in the future pastor's impregnating two girls, who both got abortions with his blessing.